Full-Frames and APS-C Compared

The Canon 5D Mark II is the update to the camera that created the $3000 full-frame DSLR market - namely the Canon 5D in 2005. Canon had this market all to their self for the first two years, but during the past year Nikon and Sony have both introduced several models to compete in the full-frame DSLR market.

The 5D2 sensor is approximately the size of a frame of 35mm film, which is 24x36mm, and resolution is 21.1MP - a significant increase from the original 5D at 12.8MP.  The new Canon 5D2 compares very well to the reolution of the recently introduced Sony A900, which at 24.6MP is the highest resolution currently available in a full-frame camera. Compare this to most other DSLR cameras today, where the sensor size is closer to APS-C size. The smaller APS-C sensor used in most other cameras results in the lenses appearing to be 150% to 200% longer than the marked focal length.  On the Canon 5D Mark II and other full-frame DSLR cameras lenses behave exactly as they would on 35mm, with no crop factor.


In the computer world, smaller and smaller traces mean higher density, more transistors, and generally better and faster performance. However, the digital sensor is not a digital device; instead, it's an analog device that gathers light and converts it into a digital signal. Thus the reverse is true in sensors in that larger sensor size is almost always better, with everything else equal. As you can see in the chart below, the APS-C sensors aren't even half of the area of a full-frame sensor. With a range of 28.1% to 42.4% of full-frame size, there is clearly a lot more information that can be potentially captured with a full-frame sensor.

DSLR Sensor Comparison
Camera Effective Sensor Resolution Sensor Dimensions and Area % of Full-Frame Sensor Density
(MP/cm2)
Olympus E-520/E-3 10 13.5x18
2.43 cm2
28.10% 4
Canon Xsi 12.2 14.8x22.2
3.28 cm2
38.00% 3.7
Sony A350 14.2 15.8x23.6
3.72 cm2
42.90% 3.8
Pentax K20D 14.6 15.6x23.4
3.65 cm2
42.20% 4
Canon 50D 15.1 14.9x22.3
3.32 cm2
38.40% 4.5
Sony A700, Nikon D300, Nikon D90 12.3 15x23.5
3.66 cm2
42.40% 3.3
Nikon D700/Nikon D3 12.1 24x36
8.64 cm2
100% 1.4
Canon 5D 12.8 24x36
8.64 cm2
100% 1.5
Canon 5D Mark II 21.1 24x36
8.64 cm2
100% 2.4
Canon 1Ds Mark III 21.1 24x36
8.64 cm2
100% 2.4
Sony A900/Nikon D3x 24.6 24x35.9
8.61 cm2
100% 2.9

The last column in the chart is the one that tells the story most accurately, however. Here the resolution of the sensor is divided by the sensor area to yield a sensor density. The lower the density, the larger the individual pixel size, and the more information that pixel can gather - all else being equal. There are a few surprises here, such as the Sony A350 being essentially the same density as the Canon XSi, and the new Canon 50D having the highest density of any current DSLR camera.

The last column does put into perspective the true potential of the full-frame sensor and sheds some light on the true meaning of Canon's 21.1MP sensor and Sony/Nikon's 24.6MP A900/D3x sensor. At 2.4MP per cm2 the 5D2 still exhibits a lower density and theoretically better high ISO performance than any current APS-C DSLR. This is very much at odds with the ridiculous claims many on the web are making about full-frame cameras going too high in resolution. In fact, sensor density on the 5D2 is significantly lower than the 10MP Canon 40D, which has a density of 3.1.

The point is that any issues the 5D2 may have with noise are not the result of pixels being "too small". All else being equal the high ISO noise should be at least as good as an 8 to 10MP Canon sensor. Where the new Canon does suffer is in comparison to sensor density of other full-frame sensors. In that metric the Canon 5D2 has about 65% more pixels per cm2 than the Nikon D3/D700 and Canon 5D, and keeping up in high ISO performance with those cameras would be quite a feat. The Canon 5D Mark II is, however, slightly lower in resolution than the Sony A900 and Nikon D3X that feature 24.6MP sensors, although the difference between 21.1 and 24.5/24.6 has to be considered negligible.

Index Canon 5D Mark II vs. Canon 5D
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  • wliang - Monday, December 08, 2008 - link

    I wonder if using IS lens for video shooting has any effect on lessen the shaking compared to non-IS lens? Reply
  • melgross - Monday, December 08, 2008 - link

    Yes, that's the point to it.

    Just make sure that when on a tripod, the lens turns the IS off.

    Canon and Nikon lenses usually know what to when on a tripod, but most others don't.
    Reply
  • cputeq - Sunday, December 07, 2008 - link

    I'm in the process of moving from Canon (40D) to Nikon (D700), but I must say the new 5D doesn't look too bad at all. I was worried the higher density was going to ruin high ISO advantages.

    I will say - I slightly prefer the D700's noise over the 5Dmii, but really it's splitting hairs - they both look great, with usable results at 12K ISO.

    I've seen images of black dots on the right side of pixels with very strong highlights - I'm wondering if any of this was experienced?

    Oh, and Anandtech, for the love of God, get a new test shot. The side of a Nvidia box is a horrible test for any type of detail rendition, though I guess with a black color it's okay for noise.


    I'm waiting on a full review of the 5D mii, but kudos to Canon from what I've seen so far, at least from this first look. It makes me *almost* regret moving to a D700 :)
    Reply
  • Zebra328 - Monday, December 08, 2008 - link

    Yes, first impression is not bad, but a second says that maybe it's only in resolution that 5d2 beats d700 but d700 seems to beat 5d2 in all the rest.
    Have a look for example at white labels with text on them, do you see how the 5d2 creates color blotches around letters? I noticed the same on the test pics from other sources as well.
    Would you confide in a camera which on a black and white surface creats blotches of pink, green, blue, etc.? How this camera would behave depicting the real scenery? Undoubtedly it would add such tiny colorful blotches in any contrasting boundary, adding color which does not belong there.
    People will look at the pics of 5d2, 5d and d700 and say:
    "Well, you know, that pic from the 5d2 has certainly more detail than those from the old 5d and d700, but the pics from the old 5d/d700 look more natural somehow, more pleasing to eye. I like them better!"
    Of course they look more pleasing and natural, as they do not contain those nasty tiny bloches of color in spots where they do not belong.
    And I don't only speak of high ISO's, the same problem is evident at any ISO, as it has to do with some flaws in the sensor of the 5d2, inadequate microlenses maybe, which act as tiny prisms creating colorful tinting in contrasting areas, or something else, I dunno.
    I know only that I was waiting so long for upgrading from my old 5d to the new 5d2, but now I'm starting to look at the d700 which performs impeccably in everything.
    Reply
  • melgross - Monday, December 08, 2008 - link

    You are so wrong here, you can't even imagine.

    Right now, the Nikon D700 is considered to be out of contention when compared to the 5D mkII. The image quality of Canon's new product so far outclasses that of the D3/700 that neither comes close.

    The poor image Wesley uses has been derided for years as being useless for telling us much of anything.

    What you need to do is to look for pictures around the net from both camera families. you will be surprised. If the other "example" you tell us you've seen, is as bad as the one here, then it's useless.

    While I am admittedly a Canon user, you seem to be a Nikon one, in the closet though you may be.

    However, while the newer Nikons did pave new road in low noise, that road has been paralleled by the 5D mkII. There may be slight differences in the way the noise is presented, as all companies use slightly different techniques, but they are about equal.

    However, when prints are made at the same size between a 12 MP camera and a 21 MP camera, the higher rez model will always look less noisy as well as more detailed, as long as the noise is about the same, which it is.
    Reply
  • Zebra328 - Monday, December 08, 2008 - link

    As I said I've got a 5d1 with quite a few Canon lenses, and I'm going to use in in future too, but at the same time I'm planning to buy a modern camera which would permit me to go into higher ISOs and, possibly, into higher resolution provided it is not achieved with a loss of other quality points.
    I haven't taken a final decision yet, and I continue to study all relevant pics that appear on the net.
    The other test pics where I noticed the same phenomenon are shown on the Imaging Resourse:
    http://www.imaging-resource.com/PRODS/E5D2/E5D2A7....">http://www.imaging-resource.com/PRODS/E5D2/E5D2A7....
    I even posted a couple of crops confronting 5d2 and d700 in a post which I entitled: "A Sensor is not Supposed to Add Color Where It does not Belong", here:
    http://forums.dpreview.com/forums/read.asp?forum=1...">http://forums.dpreview.com/forums/read.asp?forum=1...
    I only hope that it could be explained in some other way than I did, e.g. that it might be some sort of CA which definite lenses produce on a sensor with 20+ resolution, or something like that.
    I shouldn't be happy to change systems, believe me. But I do see that d700 behaves impeccably in all respects and has the only drawback of being a camera with 12 MP rather than 21.
    Reply
  • strikeback03 - Tuesday, December 09, 2008 - link

    Did you take the photos used in the DPR forum post, or find them elsewhere? Without knowing what has been done to those images, the comparison is relatively worthless. That looks like regular old color noise, at something like a 5000% zoom. Without knowing what ISO this was shot at and what was done in post processing we can't tell much else about it though.

    FWIW, the Nikon image appears to show sharpening halos at that magnification, but again I wouldn't put much into that without knowing how it was processed.
    Reply
  • melgross - Monday, December 08, 2008 - link

    I'm not quite sure what the first link is supposed to show, what with all the images there.

    But I'd like to know more about the second.

    A small amount of chrominance noise removal would eliminate that. ACR uses 25% chrominance as normal for noise reduction, with 0% luminance. I've found that doesn't detract from the sharpness at that level of setting.

    Nikon is known to use a fairly high noise removal on its files, whereas Canon, on it's semi pro and up models, uses little. That is very likely the difference you see there.

    However you do it, the 5D mkII will have much greater detail at the same print size, and the ability to go larger, or to crop. This also allows one to use stronger noise removal, which is needed for every camera to some extent, without losing as much detail.

    At the same print sizes, the Canon will have less apparent noise because of the smaller pixels in the print.

    By the way, showing images on the NET isn't the best way to see what the real world results will be. Noise tends to appear less severe in a print than it does in either PS or on a web page at 100%.
    Reply
  • melgross - Monday, December 08, 2008 - link

    I forgot to mention that the Nikon image is much mushier than the one from the Canon. lower contrast as well, though that could just be the settings. Reply
  • CEO Ballmer - Sunday, December 07, 2008 - link

    ... until the ZuneCam!

    http://fakesteveballmer.blogspot.com">http://fakesteveballmer.blogspot.com
    Reply

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